upstream changes:
----------------
7.5.3 (2021-04-07)
Features and enhancements
o Dashboard: Do not include default datasource when externally exporting dashboard with row. #32494, @kaydelaney
o Loki: Remove empty annotations tags. #32359, @conorevans
Bug fixes
o AdHocVariable: Add default data source to picker. #32470, @hugohaggmark
o Configuration: Prevent browser hanging / crashing with large number of org users. #32546, @jackw
o Elasticsearch: Fix bucket script variable duplication in UI. #32705, @Elfo404
o Explore: Fix bug where navigating to explore would result in wrong query and datasource to be shown. #32558, @aocenas
o FolderPicker: Prevent dropdown menu from disappearing off screen. #32603, @jackw
o SingleStat: Fix issue with panel links. #32721, @gjulianm
o Variables: Confirm selection before opening new picker. #32586, @hugohaggmark
o Variables: Confirm selection before opening new picker. #32503, @hugohaggmark
o Variables: Fix unsupported data format error for null values. #32480, @hugohaggmark
c223a2816a